1. Field of the Invention
The invention relates to an angle position transmitter for determining the angle position of a rotatable machine part.
2. Description of Related Knowledge
Angle position encoders are used in areas such as machine tools, robotics and automotive engineering to determine the angle position of a rotatable shaft relative to a reference position. A main component of an angle position transmitter is a transmitter disc Which can be scanned photoelectrically. The transmitter disc carries tracks to indicate the rotary motion of the machine part being monitored as transferred by a mechanically coupled transmitter shaft. Modern transmitter discs require a high resolution and a large number of tracks. Mechanical play of the transmitter shaft must be avoided to reliably obtain high resolution. The transmitter shaft of a modern angle position transmitter is typically supported by at least two antifriction bearings such as ball bearings that are, space permitting, pretensioned against each other to prevent play.
In addition to physical and mechanical problems, an angle position transmitter has the disadvantage that it can indicate absolutely angle positions only within the range of one revolution (360.degree.).